Dry etching of β-SiC in CF4 and CF4+O2 mixtures

Dry etching of cubic (100)β-SiC single crystal thin films produced via chemical vapor deposition (CVD) has been performed in CF4 and CF4+O2 mixtures, in both the reactive ion etching (RIE) and plasma etching modes. The latter process yielded measurable etch rates, but produced a dark surface layer which appears, from the results of secondary ion mass spectrometry, to be residual SiC. The RIE samples had no residual layer, but Auger electron spectroscopy did reveal a C-rich surface. The optimal RIE conditions were obtained with 10 sccm of pure CF4 at 40 mTorr and a power density of 0.548 W/cm2, giving an etch rate of 23.3 nm/min. Neither the increase of temperature between 293 and 573 K, nor the incremental addition of O2 to CF4 to 50%, produced any strong effect on the etch rates of SiC during RIE. Pictorial evidence of fine line structures produced by RIE of β-SiC films are also presented.